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-rw-r--r--src/backend/commands/variable.c18
-rw-r--r--src/backend/storage/aio/aio_init.c17
-rw-r--r--src/backend/storage/buffer/bufmgr.c5
-rw-r--r--src/backend/utils/misc/guc_tables.c16
-rw-r--r--src/backend/utils/misc/postgresql.conf.sample2
-rw-r--r--src/include/storage/bufmgr.h4
-rw-r--r--src/include/utils/guc_hooks.h2
7 files changed, 50 insertions, 14 deletions
diff --git a/src/backend/commands/variable.c b/src/backend/commands/variable.c
index 4ad6e236d69..f550a3c0c63 100644
--- a/src/backend/commands/variable.c
+++ b/src/backend/commands/variable.c
@@ -1156,6 +1156,24 @@ assign_maintenance_io_concurrency(int newval, void *extra)
#endif
}
+/*
+ * GUC assign hooks that recompute io_combine_limit whenever
+ * io_combine_limit_guc and io_max_combine_limit are changed. These are needed
+ * because the GUC subsystem doesn't support dependencies between GUCs, and
+ * they may be assigned in either order.
+ */
+void
+assign_io_max_combine_limit(int newval, void *extra)
+{
+ io_max_combine_limit = newval;
+ io_combine_limit = Min(io_max_combine_limit, io_combine_limit_guc);
+}
+void
+assign_io_combine_limit(int newval, void *extra)
+{
+ io_combine_limit_guc = newval;
+ io_combine_limit = Min(io_max_combine_limit, io_combine_limit_guc);
+}
/*
* These show hooks just exist because we want to show the values in octal.
diff --git a/src/backend/storage/aio/aio_init.c b/src/backend/storage/aio/aio_init.c
index 4e405ce7ca8..2ede7e80b65 100644
--- a/src/backend/storage/aio/aio_init.c
+++ b/src/backend/storage/aio/aio_init.c
@@ -18,6 +18,7 @@
#include "storage/aio.h"
#include "storage/aio_internal.h"
#include "storage/aio_subsys.h"
+#include "storage/bufmgr.h"
#include "storage/io_worker.h"
#include "storage/ipc.h"
#include "storage/proc.h"
@@ -72,15 +73,9 @@ AioHandleShmemSize(void)
static Size
AioHandleIOVShmemSize(void)
{
- /*
- * Each IO handle can have an PG_IOV_MAX long iovec.
- *
- * XXX: Right now the amount of space available for each IO is PG_IOV_MAX.
- * While it's tempting to use the io_combine_limit GUC, that's
- * PGC_USERSET, so we can't allocate shared memory based on that.
- */
+ /* each IO handle can have up to io_max_combine_limit iovec objects */
return mul_size(sizeof(struct iovec),
- mul_size(mul_size(PG_IOV_MAX, AioProcs()),
+ mul_size(mul_size(io_max_combine_limit, AioProcs()),
io_max_concurrency));
}
@@ -89,7 +84,7 @@ AioHandleDataShmemSize(void)
{
/* each buffer referenced by an iovec can have associated data */
return mul_size(sizeof(uint64),
- mul_size(mul_size(PG_IOV_MAX, AioProcs()),
+ mul_size(mul_size(io_max_combine_limit, AioProcs()),
io_max_concurrency));
}
@@ -160,7 +155,7 @@ AioShmemInit(void)
bool found;
uint32 io_handle_off = 0;
uint32 iovec_off = 0;
- uint32 per_backend_iovecs = io_max_concurrency * PG_IOV_MAX;
+ uint32 per_backend_iovecs = io_max_concurrency * io_max_combine_limit;
pgaio_ctl = (PgAioCtl *)
ShmemInitStruct("AioCtl", AioCtlShmemSize(), &found);
@@ -213,7 +208,7 @@ AioShmemInit(void)
ConditionVariableInit(&ioh->cv);
dclist_push_tail(&bs->idle_ios, &ioh->node);
- iovec_off += PG_IOV_MAX;
+ iovec_off += io_max_combine_limit;
}
}
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 79ca9d18d07..d04afa5ab9c 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -160,9 +160,12 @@ int maintenance_io_concurrency = DEFAULT_MAINTENANCE_IO_CONCURRENCY;
/*
* Limit on how many blocks should be handled in single I/O operations.
* StartReadBuffers() callers should respect it, as should other operations
- * that call smgr APIs directly.
+ * that call smgr APIs directly. It is computed as the minimum of underlying
+ * GUCs io_combine_limit_guc and io_max_combine_limit.
*/
int io_combine_limit = DEFAULT_IO_COMBINE_LIMIT;
+int io_combine_limit_guc = DEFAULT_IO_COMBINE_LIMIT;
+int io_max_combine_limit = DEFAULT_IO_COMBINE_LIMIT;
/*
* GUC variables about triggering kernel writeback for buffers written; OS
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index 60a40ed445a..ead80257192 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -3253,6 +3253,20 @@ struct config_int ConfigureNamesInt[] =
},
{
+ {"io_max_combine_limit",
+ PGC_POSTMASTER,
+ RESOURCES_IO,
+ gettext_noop("Server-wide limit that clamps io_combine_limit."),
+ NULL,
+ GUC_UNIT_BLOCKS
+ },
+ &io_max_combine_limit,
+ DEFAULT_IO_COMBINE_LIMIT,
+ 1, MAX_IO_COMBINE_LIMIT,
+ NULL, assign_io_max_combine_limit, NULL
+ },
+
+ {
{"io_combine_limit",
PGC_USERSET,
RESOURCES_IO,
@@ -3263,7 +3277,7 @@ struct config_int ConfigureNamesInt[] =
&io_combine_limit,
DEFAULT_IO_COMBINE_LIMIT,
1, MAX_IO_COMBINE_LIMIT,
- NULL, NULL, NULL
+ NULL, assign_io_combine_limit, NULL
},
{
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index beb05a89501..66bda60f4ca 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -200,6 +200,8 @@
#backend_flush_after = 0 # measured in pages, 0 disables
#effective_io_concurrency = 16 # 1-1000; 0 disables prefetching
#maintenance_io_concurrency = 16 # 1-1000; 0 disables prefetching
+#io_max_combine_limit = 128kB # usually 1-32 blocks (depends on OS)
+ # (change requires restart)
#io_combine_limit = 128kB # usually 1-32 blocks (depends on OS)
#io_method = worker # worker, sync (change requires restart)
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index 7f5def6bada..ecc1c3a909b 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -163,7 +163,9 @@ extern PGDLLIMPORT int maintenance_io_concurrency;
#define MAX_IO_COMBINE_LIMIT PG_IOV_MAX
#define DEFAULT_IO_COMBINE_LIMIT Min(MAX_IO_COMBINE_LIMIT, (128 * 1024) / BLCKSZ)
-extern PGDLLIMPORT int io_combine_limit;
+extern PGDLLIMPORT int io_combine_limit; /* min of the two GUCs below */
+extern PGDLLIMPORT int io_combine_limit_guc;
+extern PGDLLIMPORT int io_max_combine_limit;
extern PGDLLIMPORT int checkpoint_flush_after;
extern PGDLLIMPORT int backend_flush_after;
diff --git a/src/include/utils/guc_hooks.h b/src/include/utils/guc_hooks.h
index a3eba8fbe21..0f1e74f96c9 100644
--- a/src/include/utils/guc_hooks.h
+++ b/src/include/utils/guc_hooks.h
@@ -86,6 +86,8 @@ extern const char *show_log_timezone(void);
extern bool check_maintenance_io_concurrency(int *newval, void **extra,
GucSource source);
extern void assign_maintenance_io_concurrency(int newval, void *extra);
+extern void assign_io_max_combine_limit(int newval, void *extra);
+extern void assign_io_combine_limit(int newval, void *extra);
extern bool check_max_slot_wal_keep_size(int *newval, void **extra,
GucSource source);
extern void assign_max_wal_size(int newval, void *extra);
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-22 09:35:24 +0000